Risk of Cytomegalovirus Infection with Post-Transplantation Cyclophosphamide in Haploidentical and HLA-Matched Unrelated Donor Transplantation

Post-transplantation cyclophosphamide (PTCy) is effective for graft-versus-host disease (GVHD) prevention but is associated with an increased risk of cytomegalovirus (CMV) infection. The effect of PTCy on CMV infection in matched unrelated donor (MUD) hematopoietic stem cell transplantation (HSCT) is unclear, and whether there is any difference in CMV risk with 1 or 2 doses of PTCy is not well established. This study aimed to compare the incidence of CMV infection and the association between T cell recovery in patients who received PTCy-based GVHD prophylaxis and those who received non-PTCy-based GVHD prophylaxis. We conducted a retrospective study to compare the risk of CMV infection in 3 cohorts: cohort A (n = 94), matched related donor (MRD)/MUD HSCT with calcineurin inhibitor-based GVHD prophylaxis; cohort B (n = 103), MRD/MUD HSCT with 1 dose of PTCy, tacrolimus, and mycophenolate mofetil (MMF); and cohort C (n = 28), haploidentical donor HSCT with 2 doses of PTCy, tacrolimus, and MMF. The day +100 cumulative incidence of CMV infection was 29% for cohort A, 39% for cohort B, and 61% for cohort C (P = .009), with no difference among the cohorts in the duration of viremia (P = .46). CD3⁺ and CD4⁺ T cell counts were significantly higher in cohort A at day +30 but not at days +60 and +90. Nonrelapse mortality (NRM) trended higher and relapse was significantly lower with PTCy. There was no difference in survival among the 3 cohorts. There is an increased risk of early CMV infection in patients receiving PTCy irrespective of donor type and number of PTCy doses compared with those not receiving PTCy. Strategies focusing on CMV prevention in PTCy recipients to mitigate the risk of NRM may lead to improved long-term outcomes.